That will mean even more focus on hiring and Kalanick's unique filtering approach. He told WSJ that he prefers to get the experience of actually working with someone rather than putting them through a gauntlet of interviews.

"Simulating what it's like to work together is the best way to determine whether somebody has the raw talent to not just do the job but to grow into something bigger," Kalanick said. "It's not about doing 15 interviews with 15 different people."

Interviews can be a difficult way to figure out how someone actually works day to day, something confirmed by Google's extensive research and eventual abandonment of its notorious brainteaser interview questions.

That counters Amazon's hiring approach, which requires potential hires to interview with a series of people it calls "bar-raisers" to ensure cultural fit and try to minimize mistakes.

And for a company that is growing rapidly, Kalanick adds, you need talented employees who aren't just experts at a particular skill, but can grow, adapt, and scale with the company. That's where he says simulation beats out interviews.